As mm_half3 points out, you will still get audio from the HD-A2 when listening to HD-DVD's. At least on the case of Toshiba's HD-DVD players, this is typically done by decoding and re-encoding as high-bitrate DTS (the maximum bitrate supported by DTS, specifically - something almost never used because of the space it consumes on a disc). I've heard of many users reporting quite good results in this manner - apparently it's a clear step up from standard Dolby Digital and medium-bitrate DTS tracks found on DVD's, even if it's not the full resolution of the original track.